As one of electrical connecting apparatus of this type, there is provided an electrical connecting apparatus comprising a probe board and a plurality of probes extended from the probe board and capable of adjusting the flatness of the probe board (see Patent Document 1). According to this conventional electrical connecting apparatus, it is possible to apply pressing force or tensile force from a support member supporting the probe board to a part of the probe board. By adjusting this action force, even if bending is caused in the probe board of a probe assembly, the flatness of the probe board can be maintained by correcting the curved deformation of the probe board, thereby enabling to align the tips of the probes.
However, according to the aforementioned prior art described in Patent Document 1, it is necessary to adjust so that all the probe tips may be positioned on the same plane according to curved deformation introduced to each probe board every time the probe card assembly is assembled into the electrical connecting apparatus. The operation to adjust so that all the probe tips are adequately contact each of corresponding electrical connection terminals of the device under test is complicated and needs skill. Particularly, in an investigation of multiple integrated circuits formed on a semiconductor wafer, the number of probes of the probe assembly is remarkably increased, so that an operation to adjust to have such multiple probes adequately contact respective corresponding pads on the semiconductor wafer is not easy. Furthermore, such an adjusting operation is necessitated every time the probe assembly is replaced.
The inventors in this Application, therefore, proposed in the earlier International Patent Application (PCT/JP2005/009812) an electrical connecting apparatus which, in spite of a deformation of a probe board, dispenses with a flattening and adjusting operation of the probe board after assembling a probe assembly into an electrical connecting apparatus and which is capable of obtaining reliable electrical connection between the probes and corresponding electrical connecting terminals of an electric circuit of a device under test.
In the probe assembly of this electrical connecting apparatus, probes are formed on the probe board having a curved deformation in an unloaded free state so as to have the tips align on the same plane. By tightening a mounting bolt which penetrates a wiring board disposed between a support member and the probe board, the probe board is combined with the support member. Between a reference plane of the probe board and the support member, a cylindrical spacer is inserted, penetrating the wiring board disposed therebetween. This spacer acts to retain the deformation of the probe board at the time of tightening the mounting bolt. Thus, since the probe board is attached to the reference plane of the support member with the deformation kept as it is, all the probe tips are positioned on the same plane.
Consequently, after the probe assembly is attached to the support member, all the probe tips can be pressed substantially uniformly against each electrical connection terminal of the electric circuit which is a device under test. Thus, every time the probe assembly is replaced, too, the above-mentioned complicated flattening adjusting operation such as the conventional one can be dispensed with, thereby enabling to carry out an efficient electrical test.
In a spacer of this type, however, if both end faces are flat planes orthogonal to the axis of the spacer and an inclination is caused on the reference plane of the support member due to deflection or distortion of, e.g., the support member receiving the end faces, an end face of the spacer and the contact face of the support member for receiving the end face do not abut uniformly in the peripheral direction of the spacer, so that the contacting relation between both becomes unstable. Also, if an inclination is caused by a production error in a through hole, which permits the spacer to penetrate therethrough, formed on the wiring board to be inserted between the probe board and the support member, the contact relationship between the support member receiving the end face and the contact face of the support member which receives the end face or the contact face of the probe board becomes likewise unstable.
If the contact relationship between the end face of the spacer and the support member receiving the end face or the contact face of the probe board is unstable, slackness in tightening of the bolt supporting the probe board on the support member might be caused due to a lingered strong vibration, resulting in degradation in durability.
Patent Document 1: National Public Disclosure No. 2003-528459